MOLECULAR MECHANISM OF ACROSOMAL SWELLING REQUIRED FOR HUMAN SPERM ACROSOME REACTION

SOSA CLAUDIA; ARIAS RODOLFO; DE BLAS GERARDO ; ZANETTI NATALIA; MAYORGA LUIS; POBLETE SANTIAGO; JUSTRIBÓ GISELLA

Merlo. San Luis

Congreso; XXXV Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2017

Sociedad de Biología de Cuyo

Spermatozoa have a large secretory granule located in the apical region of the head, which undergoes a regulated calcium-dependent exocytic process called acrosomal reaction (AR). Prior to AR, the acrosome must endure deep morphological changes that involve acrosomal swelling (AS), invagination of the external acrosomal membrane and formation of intraacrosomal vesicles. Our hypothesis is that a strict regulation of water and ion input associated with cytoskeleton rearranges are necessary for AS. To test this hypothesis, we used capacitated human sperm, permeabilized with streptolysin O (SLO) ?to avoid effects due to plasma membrane channels- incubated in the presence of different water (Ag+, Hg2+), K+ (Ap, 4AP) and Cl- channels (NPPB, DIDS) inhibitors and actin polymerization blockers (latrunculin b, cofilin 1), stimulated with 10 µM free calcium. Percentage of AR was evaluated by staining sperm with FITC-PSA and acrosomal status by transmission electron microscopy. We observed that water, K+ and Cl- antagonists inhibited the AS and AR. Latrunculin b and cofilin 1 also reduced both processes. Our results suggest that water and K+-Cl- channels, as well as actin filament polymerization, are required for AS and AR in human sperm.